Investigate mechanisms of attachment of normal and pathologic bacteria to the urethral epithelium: beginning with analysis of normal canine urethral flora, studying its replacement by pathologic flora; continuing with study of specific adherence to urethral cells in vitro and in vivo, with special reference to parts played by certain bacterial species, by epithelial cellular activity, and by secretory immune reactions; concluding with determination of effects of intermittent voiding (washout) on bacterial adherence.